Riding exerciser



FIG. 1 is a perspective view of the riding exerciser;

FIG. 2 is a front elevational view of the riding exerciser;

FIG. 3 is a left side elevational view of the riding exerciser;

FIG. 4 is a right side elevational view of the riding exerciser;

FIG. 5 is a top view of the riding exerciser; and,

FIG. 6 is a bottom view of the riding exerciser. 

The ornamental design for a riding exerciser, as shown and described. 